JP2000292202A - Magnetic rotary encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a strain originating in an output signal of a second magnetic detection element to corresponding to a rotating signal generating part. SOLUTION: A first magnetic detection element 26 in a magnetic sensor 11 is opposed to a referential position signal generating part 46 in a rotating body 41, and a second magnetic detection element 27 is opposed to a rotating signal generating part 47. A notch part 48 is formed between a convex part 46a of the referential position signal generating part 46 and the rotating signal generating part 47. Since the convex part 46a of the generating part 46 and the rotating signal generating part 47 are separated in a row direction by the notch part 48, influence of the convex part 46a of the part 46 to the second magnetic detection element 27 corresponding to the rotating signal generating part 47 is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic rotary encoder provided with a rotating body having a reference position signal generator and a rotation signal generator.

[0002]

Conventionally, there has been a magnetic rotary encoder for detecting, for example, the number of revolutions of a motor using magnetism. As shown in FIG. 6, this includes a gear-shaped rotator 1 and a magnetic sensor 2.

The rotating body 1 is made of a magnetic material and has a reference position signal generator 3 having only one convex portion 3a on the outer periphery.
And a rotation signal generator 4 having a plurality of projections 4a on its outer periphery at equal intervals, which are integrally mounted on a rotating shaft of a motor (not shown) so as to rotate integrally therewith. The magnetic sensor 2 has a case 5 in which first and second magnetic detecting elements 6 and 7 each composed of, for example, a magnetoresistive element, a bias magnet 8 and the like are housed. Is attached to a predetermined portion so as to face from the outer peripheral portion. In this case, the upper first magnetic detection element 6 is arranged so as to face the reference position signal generator 3, and the lower second magnetic detection element 7 is arranged so as to face the rotation signal generator 4.

In the above configuration, when the rotating body 1 rotates, the magnetic flux linked to the first and second magnetic detecting elements 6 and 7 changes, and accordingly, the first and second magnetic detecting elements 6 and 7 change. Since the output signal output from 7 changes, it is possible to detect the rotation speed of the rotating body 1 and thus the motor by detecting the change of the output signal.

Here, when the rotating body 1 rotates, the first
The waveform diagram of FIG. 8 is ideal for the waveforms of the output signal (position signal) of the magnetic detection element 6 and the output signal (rotation signal) of the second magnetic detection element 7.

However, in the above-described conventional configuration, as shown in FIG. 7, when one convex portion 3a of the reference position signal generating section 3 passes near the magnetic sensor 2, the convex portion 3a Due to the influence, there is a problem that the output signal (rotation signal) of the second magnetic detection element 7 corresponding to the rotation signal generation unit 4 is distorted. The distortion of the output signal is caused by the rotating body 1
This becomes more remarkable as the rotation speed increases.

The present invention has been made in view of the above circumstances, and has as its object the second object corresponding to the rotation signal generator.
Another object of the present invention is to provide a magnetic rotary encoder capable of suppressing the occurrence of distortion in the output signal of the magnetic detection element.

[0008]

In order to achieve the above-mentioned object, a first aspect of the present invention has a reference position signal generating section made of a magnetic material having one convex portion on an outer peripheral portion. A rotating body that is disposed near the position signal generating section and has a rotation signal generating section made of a magnetic material having a large number of convex portions on the outer periphery thereof, and is attached to a rotating member and rotates, and the reference position signal generating section includes: A magnetic sensor having a first magnetic detecting element arranged to face from the outer peripheral part and a second magnetic detecting element arranged to face the rotation signal generating part from the outer peripheral part; Wherein a notch is formed between the projection of the reference position signal generator and the rotation signal generator.

According to the above-described means, the convex portion of the reference position signal generating section and the rotation signal generating section are separated from each other by the notch in the arrangement direction. In addition, the influence on the second magnetic detection element corresponding to the rotation signal generating unit is reduced, so that it is possible to suppress the occurrence of distortion in the output signal of the second magnetic detection element.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, in FIGS. 1 to 4, a housing 12 is formed inside a case 12 of a magnetic sensor 11, a rectangular opening 14 is formed in a portion serving as a front detection surface, and an opening is also formed in a rear portion. An insertion opening 15 larger than the portion 14 is formed. Storage unit 1
3 communicates with the opening 14 and the insertion opening 15. A rectangular frame 16 protrudes from the periphery of the opening 14, and mounting holes 17 are formed at four locations around the frame 16.

On the front surface of the case 12, a plate 18 in the shape of a shallow container is arranged so as to cover the opening 14 and the frame 16 from the front. On plate 18,
The portion corresponding to the opening 14 is a detection surface 18a. The plate 18 is formed of a thin plate having a thickness of about 0.1 mm. Four screw insertion holes 19 are formed in the flange portion 18 b at the peripheral portion of the plate 18 so as to correspond to the mounting holes 17. A paste-like sealing material 20 (see FIG. 4) is applied to the front surface of the frame portion 16, and the sealing material 20 is interposed between the front surface of the frame portion 16 and the inner surface of the plate 18.

A rectangular frame-shaped frame 21 is arranged on the front side of the plate 18 so as to press the flange 18b, which is the peripheral portion of the plate 18, from the front side.
The frame 21 also has four screw insertion holes 22 corresponding to the screw insertion holes 19. In this case, the case 12, the plate 18, and the frame 21 are each formed of aluminum, which is a non-magnetic material.

The screw insertion hole 22 of the frame 21
The plate 18 is mechanically fixed to the front surface of the case 12 by screwing each screw 23 sequentially inserted through the screw insertion hole 19 of the plate 18 into the corresponding mounting hole 17 of the case 12.

As shown in FIGS. 1 and 2, a sensor unit 24 is housed in the housing 13 of the case 12. A sensor IC 28 having first and second magnetic detecting elements 26 and 27 each composed of a magnetoresistive element (MRE) is provided at a front portion of the holder 25 of the sensor unit 24, and a rear portion of the sensor IC 28 is provided. Side, and a bias magnet 2 which is a magnet generating means.
9 and two circuit boards 30a and 30b. The first and second magnetic detecting elements 26 and 27 are arranged vertically when viewed from the front. Among them, the first magnetic detecting element 26 is for detecting a reference position signal, and the second magnetic detecting element 2
Reference numeral 7 is for detecting a rotation signal. Two circuit boards 30
A plurality of output adjustment volumes 31 are provided on the circuit board 30b located at the upper part of the components a and 30b.

The sensor unit 24 is inserted into the storage unit 13 through the rear insertion opening 15 and the holder 25 is fixed in the storage unit 13 by tightening the screw 32 from the insertion opening 15 side. It is arranged. In this arrangement state, the first and second magnetic detecting elements 26 and 27 are in close contact with the inner surface of the plate 18. The case 12 has an opening formed at a position corresponding to the volume 31 and a cover 33 for closing the opening.
Are attached by screws 34. Case 1
A rear cover 35 is also attached to the rear of the device 2 with screws 36 so as to close the insertion opening 15.

The magnetic sensor 11 thus configured is
The stay 38 is attached to a stay 38 by a screw 37, and the stay 38 is attached to the attaching portion 4 by a screw 39 (see a two-dot chain line in FIG.
By fixing to 0 (see the two-dot chain line in FIG. 1), it is arranged in the vicinity of the rotating body 41 which is the object to be detected. in this case,
Between the case 12 of the magnetic sensor 11 and the stay 38,
As shown in FIG. 1, a compression coil spring 42 for urging the magnetic sensor 11 away from the rotating body 41 and a position adjusting screw 43 are provided, and the position adjusting screw 43 is rotated to advance and retreat. Thus, the gap 44 between the position of the magnetic sensor 11 with respect to the rotating body 41, and thus the outer peripheral portion of the rotating body 41 and the detection surface 18a of the magnetic sensor 11
Can be adjusted. Here, stay 38
, The compression coil spring 42 and the position adjusting screw 43 constitute a position adjusting mechanism 45 of the magnetic sensor 11.

The rotating body 41 is made of a magnetic material, and includes a reference position signal generator 46 having only one mountain-shaped projection 46a on the outer periphery and a plurality of mountain-shaped projections 47a on the outer periphery at equal intervals. And the rotation signal generator 47 having
For example, it is attached to a rotating shaft of a motor (not shown) so as to rotate integrally therewith. In this case, a cutout portion 48 for forming a gap between the reference position signal generating portion 46 and the rotation signal generating portion 47 is formed below the convex portion 46a. In the magnetic sensor 11, the first magnetic detecting element 26 faces the reference position signal generating section 46, and the second magnetic detecting element 27 faces the rotation signal generating section 47 from the outer peripheral portion via the detection surface 18a. Are arranged as follows.

In the above configuration, when the rotating body 41 rotates, the magnetic flux linked to the first and second magnetic detecting elements 26 and 27 changes, and accordingly, the first and second magnetic detecting elements 26 and 27 change. Since the output signal output from 27 changes, by detecting the change in the output signal, it is possible to detect the rotation speed of the rotating body 41, and thus the motor.

Here, in the above-described embodiment, the notch 48 is formed between the projection 46a of the reference position signal generator 46 and the rotation signal generator 47 in the rotating body 41, so that the reference position signal The projection 46a of the generator 46 and the rotation signal generator 47 are separated by the notch 48 in the direction in which they are arranged (vertically). Therefore, the influence of the protrusion 46a of the reference position signal generator 46 on the second magnetic detection element 27 corresponding to the rotation signal generator 47 is reduced, and as shown in FIG. Thus, it is possible to suppress the occurrence of distortion in the output signal (rotation signal) of the second magnetic detection element 27.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. As the magnetic detecting elements 26 and 27, Hall elements can be used instead of the magnetoresistive elements. The reference position signal generator 46 and the rotation signal generator 47 in the rotating body 41 may be configured as separate components.

[0021]

As is apparent from the above description, according to the magnetic rotary encoder of the present invention, the projection of the reference position signal generator and the rotation signal generator are separated in the direction of arrangement by the notch. In this state, the influence of the projection of the reference position signal generation unit on the second magnetic detection element corresponding to the rotation signal generation unit is reduced.
This can suppress the occurrence of distortion in the output signal of the magnetic detection element.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view

FIG. 3 is a front view of a magnetic sensor.

FIG. 4 is an exploded perspective view of a case portion of the magnetic sensor.

FIG. 5 is a waveform diagram of output signals of the first and second magnetic detection elements.

FIG. 6 is a diagram corresponding to FIG. 1 of a conventional example.

FIG. 7 is a diagram corresponding to FIG. 5 of a conventional example.

FIG. 8 is a waveform diagram of an ideal output signal of the first and second magnetic sensing elements.

[Explanation of symbols]

11 is a magnetic sensor, 26 is a first magnetic detecting element, 27 is a second magnetic detecting element, 29 is a bias magnet, 41
Is a rotating body, 46 is a reference position signal generating section, 46a is a convex section,
Reference numeral 47 denotes a rotation signal generator, 47a denotes a projection, and 48 denotes a notch.

Claims (1)

[Claims] 1. A magnetic material having a reference position signal generating portion made of a magnetic material having one convex portion on an outer peripheral portion, and having a plurality of convex portions on an outer peripheral portion arranged near the reference position signal generating portion. A rotating body having a body-made rotation signal generating unit, mounted on a rotating member and rotating; a first magnetic detection element arranged to face the reference position signal generating unit from an outer peripheral portion; and the rotation signal A magnetic sensor having a second magnetic detection element disposed so as to face the generating portion from the outer peripheral portion, between the convex portion of the reference position signal generating portion and the rotation signal generating portion in the rotating body. A magnetic rotary encoder characterized in that a notch is formed in the rotary encoder.